This study will look at the use and impact of smartphone application (app) for adolescents with ongoing pain caused by their juvenile idiopathic arthritis (JIA).The current project will include three studies. First, the investigators conducted usability sessions with adolescents with JIA to refine the app so that it is usable, acceptable and understandable. The aim of this study is to look at (a) how regularly the "iCanCope with Pain" app is used and (b) any effect the app has on young people's health. This study will compare two groups of young people: one that is using the new app, and one that receives usual medical care.